I've used concealment tree a lot, and I can tell you that is a tree only valuable for pvp, in a 1vs1 fight concealment operative can win really easy, especially if you use double hidden strike (cloaking screen during fight), for a great pvp rotation against single target I can suggest you: Hidden strike, Backstab, Shiv, Debilitate, Laceration, Explosive probe, Laceration (if the target is still alive It's probably a tank, repeat all the rotation with the help of your stim boost and cloaking screen for another hidden strike) remember to keep your acid blade always up .
In pve that tree It's not really good and It's almost impossible to compete with a mara or a sniper in a long boss fight (even if you use letalithy).
I also recently respec my operative as a healer and It's another story in pve, as a healer you will be much usefull to your raid.